1. Field of the Invention
The present invention relates to a method of forming a pattern by using an electroconductive composition. More particularly, the present invention concerns a method of forming a fine resist pattern by using an electroconductive composition having a property such that an accumulation of charges is avoided when a resist pattern is formed.
2. Description of the Related Art
The thin film-forming technique and the photographic etching technique are widely used for the formation of electronic circuit elements having a fine pattern, such as semiconductor elements. More specifically, thin films layers such as an electroconductive layer and an insulating layer are formed on a substrate by the sputtering method, the chemical vapor phase growth method or the like, and then a resist (photosensitive resin) is coated by the spin-coating method or the like and exposed to light, and by utilizing the difference of the solubility of the resist in a liquid developer in the exposed area and in the unexposed area, a pattern is formed. Then, using the formed resist pattern as a mask, a wet etching or dry etching is carried out to form a fine conductor pattern or insulating layer pattern on the substrate.
As the light source for the exposure of the resist, ultraviolet rays, excimer laser beams, X-rays, electron beams, and focusing ion beams are used. The lithography process using electron beams, among these light sources, is widely utilized for the production of masks, the trial production of logic circuits, and the production of minute-quantity multiple-grade type LSI's such as ASIC, the need for which has recently increased, because patterning can be directly performed without using a mask. Focusing ion beams, by which a direct patterning is possible, show a good straight-advance property and a superior, because little scattering occurs in the resist. Accordingly, the application of focusing ion beams to the production of fine devices, for which a fine processing is required, is under investigation.
Nevertheless, since resist materials for electrons or focusing ion beams are usually insulators, when the exposure is carried out by using electron beams or ion beams, an accumulation of charges, i.e., a charge-up, occurs, and a misregistration of the pattern is obtained. This misregistration of the pattern is increased as the pattern becomes finer, and the problem of the misregistration of the pattern becomes more serious with each increase of the degree of integration.
To prevent this charge-up, attempts have been made to coat aluminum or a treating agent such as an electroconductive polymer on a resist, but this method of preventing a charge-up by coating aluminum is defective in that the process steps are complicated. The method using a treating agent such as an electroconductive polymer is advantageous in that the steps are simple, but since a material showing a sufficient resistance to a charge-up has not been found, this method is not in use in practice.